It can simply be said that when playing a video, the audio either runs ahead of the video or it might run behind the video. AV synchronization can be an issue in TV, videoconferencing, or film.

Sound to-video synchronization (AV synchronization, otherwise called lip-sync, or by its absence: lip-sync blunder, lip fold) alludes to the overall planning of sound and video parts during creation, after creation (blending), transmission, gathering, and play-back handling. Common Audio and Video Out of Sync Issues Read the H.264 encoding guide for more about that, or call x264 -fullhelp for the preset description.For macOS 10.11 or later Part 1. They have names like ultrafast, superfast, veryfast, faster, fast, medium, slow, slower or veryslow. Those presets have nothing to do with ffmpeg's presets, and they're called with the -preset option. It has several presets which basically control the speed of the encoder in inverse relation to the quality or efficiency of the encoding process. X264 presets: x264 is an H.264 encoder (used in ffmpeg with -c:v libx264). avpreset files: work similar to -vpre or -apre presets - those are mostly for compatibility with Libav.

For example, you simply call -pre custom, and ffmpeg will load the custom.ffpreset file. This allows you to set video and audio encoders at the same time.

You can also, more generally, use -pre and specify vcodec=libvpx as an option/value pair in the. For example, if you set -vcodec libvpx (or -c:v libvpx), and -vpre 1080p, then ffmpeg will load the libvpx-1080p.ffpreset file. Depending on the encoder you select, ffmpeg will then search for a matching ffpreset file. ffpreset files: You define option=value pairs in those files and for video settings you generally use them with -vpre. Note that there are three different kinds of presets:

Instead of reading the Arch Wiki, rather check the ffmpeg documentation on the preset options.

How to use ffmpeg superuser